Abstract Details

Title Anti-GAD65 Antibody: a Possible Link to Encephalopathy, Aphasia, Seizures and Lateralized Weakness

Topic Autoimmune Neurology

Presentation(s) P2 - Poster Session 2 (5:30 PM-6:30 PM)

Poster/Presentation
Number 15-021

Objective

To describe an unusual presentation of anti-GAD65 antibody encephalitis

Background GAD65 enzyme mediates the formation of inhibitory neurotransmitter GABA. Autoantibodies have been associated with diabetes, limbic encephalitis, stiff-person and cerebellar syndromes.

Design/Methods A 74-year-old man with a history of HTN, HLD, CAD, and alcohol use presented with several months of word finding difficulties, spatial disorientation, arm clumsiness and frequent falls. These acutely worsened a week prior to presentation with fluent aphasia, left gaze, right hemiparesis and neglect. MRI brain was unremarkable. His encephalopathy progressed to include agitation, hand tremors and myoclonic jerks with subsequent generalized seizure, leading to intubation.

Results

EEG showed diffuse left>right slowing. Second MRI brain showed linear hyperintensity in the right cerebellum. CSF had normal WBC, protein and glucose. CSF HSV 1/2, viral encephalitis, paraneoplastic, 14-3-3 were negative as were serum Lyme, RPR, ANA, B12, thiamine, ethanol and toxicology. Serum autoimmune encephalopathy evaluation revealed anti-GAD65 antibody at 60 times the upper limit of reference range. Body CT imaging was negative for malignancy.

He was initially treated with thiamine, valproate and lacosamide and extubated with improved mental status. Left gaze, aphasia and right hemiparesis resolved though intermittent delirium persisted. After five days of IVIG, he was discharged to inpatient rehabilitation. At two months follow up, family noted substantial resolution of language and visuospatial deficits and marked gait improvement. Mild parkinsonism, including rigidity, shuffling gait and grasp signs remained.

Conclusions Anti-GAD65 antibody is associated with numerous neurologic syndromes. In this case, acute encephalopathy, left cerebral dysfunction, and seizures were likely secondary to an autoimmune encephalitis, which was gradually halted by IVIG. This unusual presentation with subacute cortical deficits, frontal release signs, and mild parkinsonism further suggests a concomitant underlying neurodegenerative disorder. Clinicians should consider anti-GAD65 antibody autoimmune encephalitis in patients presenting with encephalopathy with focal deficits without a clear vascular or ictal cause.

Authors/Disclosures
Gabriela Tantillo, MD (Baylor College of Medicine) PRESENTER	Dr. Tantillo has received personal compensation in the range of $500-$4,999 for serving as a faculty honorarium for educational symposium with American Epilepsy Society.
Rory Abrams, MD (Icahn School of Medicine At Mount Sinai)	Dr. Abrams has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Averitas Pharmaceutical.
Nishant K. Mishra, MD, MBBS, PhD, FESO (Yale University)	Dr. Mishra has nothing to disclose.
Elizabeth Pedowitz, MD (Memorial Sloan Kettering Cancer Center)	No disclosure on file
Stephen Krieger, MD, FAAN (Mount Sinai Dept of Neurology)	Dr. Krieger has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Biogen. Dr. Krieger has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for EMD Serono. Dr. Krieger has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Genentech. Dr. Krieger has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Novartis. Dr. Krieger has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for TG Therapeutics. Dr. Krieger has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Sanofi. Dr. Krieger has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Cycle. The institution of Dr. Krieger has received research support from Novartis. The institution of Dr. Krieger has received research support from Bristol Myers Squibb. The institution of Dr. Krieger has received research support from Biogen. The institution of Dr. Krieger has received research support from Sanofi.
Anusha Yeshokumar, MD (Icahn School of Medicine at Mount Sinai)	Dr. Yeshokumar has nothing to disclose.

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